This new microscope technology uses helium ions to generate the signal used to image extremely small objects, a technique analogous to the scanning electron microscope, which was first introduced commercially in the 1960s. Paradoxically, although helium ions are far larger than electrons, they can provide higher resolution images with higher contrast. The depth of field is much better with the new technology too, so more of the image is in focus.
“It is the physics,” explains Andras Vladar, SEM project leader in NIST’s Nanoscale-Metrology Group. “Ions have larger mass and shorter wavelength than electrons, so they can be better for imaging.” The images, he says, appear almost three-dimensional, revealing details smaller than a nanometer—the distance spanned by only three atoms in the silicon crystal.
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